Abstract
Kinetochores mediate microtubule-chromosome attachment and ensure accurate segregation of sister chromatids. The highly conserved Ndc80 kinetochore complex makes direct contacts with the microtubule and is essential for spindle checkpoint signaling. It contains a long coiled-coil region with globular domains at each end involved in kinetochore localization and microtubule binding, respectively. We have directly visualized the architecture of the yeast Ndc80 complex and found a dramatic kink within the 560-A coiled-coil rod located about 160 A from the larger globular head. Comparison of our electron microscopy images to the structure of the human Ndc80 complex allowed us to position the kink proximal to the microtubule-binding end and to define the conformational range of the complex. The position of the kink coincides with a coiled-coil breaking region conserved across eukaryotes. We hypothesize that the kink in Ndc80 is essential for correct kinetochore geometry and could be part of a tension-sensing mechanism at the kinetochore.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence
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Chromosomal Proteins, Non-Histone / chemistry
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Chromosomal Proteins, Non-Histone / metabolism
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Humans
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Kinetochores* / chemistry
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Kinetochores* / metabolism
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Macromolecular Substances* / chemistry
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Macromolecular Substances* / metabolism
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Microscopy, Electron
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Microtubules / chemistry
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Microtubules / metabolism
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Mitosis / physiology
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Models, Molecular
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Molecular Sequence Data
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Nuclear Proteins / chemistry*
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Nuclear Proteins / metabolism
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Nuclear Proteins / ultrastructure
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Protein Conformation*
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / metabolism
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Saccharomyces cerevisiae Proteins / ultrastructure
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Sequence Alignment
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Stress, Mechanical
Substances
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Chromosomal Proteins, Non-Histone
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Macromolecular Substances
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NDC80 protein, S cerevisiae
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Nuclear Proteins
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Saccharomyces cerevisiae Proteins
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Spc24 protein, S cerevisiae
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Spc25 protein, S cerevisiae